Such an antenna is disclosed in our co-pending British Patent Application No. 9517086.6, the entire disclosure of which is incorporated in this present application so as to form part of the subject matter of this application as first filed. The earlier application discloses a quadrifilar antenna having two pairs of diametrically opposed helical antenna elements, the elements of the second pair following respective meandered paths which deviate on either side of a mean helical line on an outer cylindrical surface of the core so that the elements of the second pair are longer than those of the first pair which follow helical paths without deviation. Such variation in the element lengths makes the antenna suitable for transmission or reception of circularly polarised signals.
The applicants have found that such an antenna tends to favour reception of elliptically rather than circularly polarised signals, and it is an object of the present invention to provide for enhanced reception of circularly polarised signals.